Re: [syzbot] [bluetooth?] general protection fault in l2cap_sock_recv_cb

syzbot
2024-06-11T02:47:04Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in smack_socket_sock_rcv_skb

==================================================================
BUG: KASAN: slab-use-after-free in smack_socket_sock_rcv_skb+0xec/0x13a0 security/smack/smack_lsm.c:4142
Read of size 8 at addr ffff88807ae86498 by task kworker/u9:2/5148

CPU: 1 PID: 5148 Comm: kworker/u9:2 Not tainted 6.10.0-rc1-syzkaller-00267-gcc8ed4d0a848-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: hci0 hci_rx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
smack_socket_sock_rcv_skb+0xec/0x13a0 security/smack/smack_lsm.c:4142
security_sock_rcv_skb+0x6d/0xa0 security/security.c:4603
sk_filter_trim_cap+0x184/0xa80 net/core/filter.c:150
sk_filter include/linux/filter.h:945 [inline]
l2cap_sock_recv_cb+0x176/0x580 net/bluetooth/l2cap_sock.c:1504
l2cap_conless_channel net/bluetooth/l2cap_core.c:6780 [inline]
l2cap_recv_frame+0x8b6d/0x10670 net/bluetooth/l2cap_core.c:6833
hci_acldata_packet net/bluetooth/hci_core.c:3842 [inline]
hci_rx_work+0x50f/0xca0 net/bluetooth/hci_core.c:4079
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 5966:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:4121 [inline]
__kmalloc_noprof+0x1f9/0x400 mm/slub.c:4134
kmalloc_noprof include/linux/slab.h:664 [inline]
sk_prot_alloc+0xe0/0x210 net/core/sock.c:2080
sk_alloc+0x38/0x370 net/core/sock.c:2133
bt_sock_alloc+0x3c/0x340 net/bluetooth/af_bluetooth.c:148
l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1873 [inline]
l2cap_sock_create+0x13f/0x2d0 net/bluetooth/l2cap_sock.c:1913
bt_sock_create+0x161/0x230 net/bluetooth/af_bluetooth.c:132
__sock_create+0x490/0x920 net/socket.c:1571
sock_create net/socket.c:1622 [inline]
__sys_socket_create net/socket.c:1659 [inline]
__sys_socket+0x150/0x3c0 net/socket.c:1706
__do_sys_socket net/socket.c:1720 [inline]
__se_sys_socket net/socket.c:1718 [inline]
__x64_sys_socket+0x7a/0x90 net/socket.c:1718
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5965:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2195 [inline]
slab_free mm/slub.c:4436 [inline]
kfree+0x149/0x360 mm/slub.c:4557
sk_prot_free net/core/sock.c:2116 [inline]
__sk_destruct+0x476/0x5f0 net/core/sock.c:2208
l2cap_sock_release+0x15b/0x1d0 net/bluetooth/l2cap_sock.c:1417
__sock_release net/socket.c:659 [inline]
sock_close+0xbc/0x240 net/socket.c:1421
__fput+0x406/0x8b0 fs/file_table.c:422
__do_sys_close fs/open.c:1555 [inline]
__se_sys_close fs/open.c:1540 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1540
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807ae86000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1176 bytes inside of
freed 2048-byte region [ffff88807ae86000, ffff88807ae86800)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7ae80
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffefff(slab)
raw: 00fff00000000040 ffff888015042000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080080008 00000001ffffefff 0000000000000000
head: 00fff00000000040 ffff888015042000 dead000000000122 0000000000000000
head: 0000000000000000 0000000080080008 00000001ffffefff 0000000000000000
head: 00fff00000000003 ffffea0001eba001 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5658, tgid 5658 (syz-executor), ts 103136223027, free_ts 103057739028
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1468
prep_new_page mm/page_alloc.c:1476 [inline]
get_page_from_freelist+0x2e2d/0x2ee0 mm/page_alloc.c:3402
__alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4660
__alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
alloc_slab_page+0x5f/0x120 mm/slub.c:2264
allocate_slab+0x5a/0x2e0 mm/slub.c:2427
new_slab mm/slub.c:2480 [inline]
___slab_alloc+0xcd1/0x14b0 mm/slub.c:3666
__slab_alloc+0x58/0xa0 mm/slub.c:3756
__slab_alloc_node mm/slub.c:3809 [inline]
slab_alloc_node mm/slub.c:3988 [inline]
__do_kmalloc_node mm/slub.c:4120 [inline]
__kmalloc_noprof+0x257/0x400 mm/slub.c:4134
kmalloc_noprof include/linux/slab.h:664 [inline]
kzalloc_noprof include/linux/slab.h:778 [inline]
ip6t_alloc_initial_table+0x71/0x640 net/ipv6/netfilter/ip6_tables.c:40
ip6table_mangle_table_init+0x1c/0x70 net/ipv6/netfilter/ip6table_mangle.c:82
xt_find_table_lock+0x2d4/0x3b0 net/netfilter/x_tables.c:1260
xt_request_find_table_lock+0x26/0x100 net/netfilter/x_tables.c:1285
get_info net/ipv6/netfilter/ip6_tables.c:979 [inline]
do_ip6t_get_ctl+0x89e/0x1820 net/ipv6/netfilter/ip6_tables.c:1668
nf_getsockopt+0x299/0x2c0 net/netfilter/nf_sockopt.c:116
ipv6_getsockopt+0x263/0x380 net/ipv6/ipv6_sockglue.c:1494
tcp_getsockopt+0x163/0x1c0 net/ipv4/tcp.c:4399
page last free pid 4534 tgid 4534 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1088 [inline]
free_unref_page+0xd19/0xea0 mm/page_alloc.c:2565
__slab_free+0x31b/0x3d0 mm/slub.c:4347
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3940 [inline]
slab_alloc_node mm/slub.c:4000 [inline]
kmem_cache_alloc_noprof+0x135/0x2a0 mm/slub.c:4007
getname_flags+0xbd/0x4f0 fs/namei.c:139
do_sys_openat2+0xd2/0x1d0 fs/open.c:1399
do_sys_open fs/open.c:1420 [inline]
__do_sys_openat fs/open.c:1436 [inline]
__se_sys_openat fs/open.c:1431 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1431
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88807ae86380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807ae86400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807ae86480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807ae86500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807ae86580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: cc8ed4d0 Merge tag 'drm-fixes-2024-06-01' of https://g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=147f0d02980000
kernel config: https://syzkaller.appspot.com/x/.config?x=47d282ddffae809f
dashboard link: https://syzkaller.appspot.com/bug?extid=b7f6f8c9303466e16c8a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=11e10922980000